HLA Genotype Compatibility Assessment for Transplantation

Introduction to HLA Compatibility

The two HLA genotypes presented show significant mismatches at multiple loci, which would likely result in a high risk of rejection and graft failure in solid organ transplantation, particularly kidney transplantation where HLA-DQ matching is increasingly recognized as critical for long-term outcomes 1, 2

Mismatches at HLA-A loci: A29:02:01:01/A03:01:01:01 vs. A01:01:01/A02:01P 1
Mismatches at HLA-B loci: B15:01:01:01/B44:03:01:01 vs. B38:01:01/B44:02:01 1, 3
Partial match at HLA-C loci: C16:01:01:01/C03:03:01:01 vs. C05:01:01/C12:03:01 1
Partial match at HLA-DRB1: DRB104:04:01:14/DRB113:01:01:03 vs. DRB104:01:01G/DRB113:01P 2, 4
Mismatches at HLA-DQB1: DQB104:04:01:14/DQB106:03:01:01 vs. DQB103:01:01/DQB106:03:01 2, 4
Mismatches at HLA-DQA1: DQA103:01:01:01/DQA101:03:01:02 vs. DQA101:03:01/DQA103:03:01 2, 4
Partial match at HLA-DPB1: DPB103:01/DPB104:01 vs. DPB102:01/DPB104:01 2

HLA-DQ mismatches significantly increase the risk of graft loss in both living and deceased donor kidney transplantation (HR 1.12) 5
HLA-DQ donor-specific antibodies (DSAs) are particularly strong, persistent, and resistant to treatment 5
Patients with 2 HLA-DQ mismatches in their first graft have >50% chance of becoming highly sensitized if they need retransplantation 5
The DQA1/DQB1 pairing (DQ heterodimer) is critical, as both chains contribute to immunogenicity 3, 4

High-resolution molecular typing is essential for accurate assessment of compatibility 3
Both genotypes show allele-level typing, which is more informative than antigen-level typing 1
The frequency of specific HLA alleles varies significantly between ethnic groups, which impacts matching probability 3, 6

Consider these genotypes as poorly matched for solid organ transplantation, particularly for kidney transplantation 1, 5
For kidney transplantation, the HLA-DQ mismatches are especially concerning for long-term outcomes 2, 5
If transplantation is necessary despite these mismatches, closer monitoring for rejection and DSA development would be warranted 4, 5

For patients with rare HLA types, consideration of broader geographic sharing may improve matching 6, 7
"Sliding scale" point systems in allocation algorithms can help balance equity and utility for patients with uncommon HLA phenotypes 6, 7
Molecular mismatch analysis (epitope matching) may eventually provide more nuanced assessment of compatibility beyond simple allele matching 8

Focusing only on antigen-level matching rather than allele-level differences (e.g., B44:02 vs. B44:03) 3
Neglecting the importance of HLA-DQ matching, which has historically been underemphasized 2, 5
Failing to consider both chains of the HLA-DQ molecule (DQA1 and DQB1) when assessing compatibility 3, 4
Not accounting for ethnic differences in HLA frequency when interpreting matching probability 3, 6